Now what?

I went outside to get some pictures for my boyfriend of some stuff he is selling. While I was out there I heard the sounds of an awful cat fight coming from inside the barn. I ran in there and found a HUGE yellowish tom cat severely attacking Louie, the elderly Siamese that lives here. I've never seen the tom cat before. I chased the yellow cat off but he only ran under the room in the barn and Louie ran off and hid too, he didn't seem injured but I won't know until I find him again. I set the trap with some leftover KFC, and I've been sitting out there for about an hour making sure there are no more fights. When I can find Louie, he's coming indoors until the tom cat is caught. Louie is 10+ years old, and is a sweet elderly gentleman... he doesn't deserve being beat up by a young stranger. Now I'm wondering if maybe that's what happened to Marley... maybe he got beat up when we weren't around and didn't make it? I haven't seen the young black cat in awhile either..
The tom cat certainly cannot stay here, and the local shelter will not take him... any ideas what I should do? Normally the cats are TNR but this cat isn't staying around if he's going to be hurting the other cats.

Was Marley the Siamese you haven't been able to find? (you posted a picture of a Siamese cat in your other thread about checking your trap too often). I was hoping you would have found him by now. Hopefully, your little black cat will show up again, too.

Is Louie neutered? There's always a pecking order among cats, with unneutered cats at the top. With this tom, it's either that, or he was fighting with Louie over food.

I think your only option is to catch the tom cat and get him neutered. Don't release him miles away (however tempted you might be). Release him in your area, but not on your property. You have to assume he's familiar with the surrounding area since you don't know for sure where he's come from. Familiar territory (and neutering) will give him the best chance for survival.

If he does eventually find his way back to your house, hopefully the neuter will have calmed him down by that time.

Yes, Marley was the other Siamese that I haven't been able to find. I think either the big yellow cat chased him off or injured him.
Louie is neutered, he was already neutered when he was dropped off a year ago. He's very laid back and won't start a fight... and he doesn't even really try to defend himself. And there wasn't any food out at the moment, they get fed in the evening only right now because I've been trying to trap.
As of right now, I haven't caught the yellow cat yet, and haven't found Louie yet, I've been out there every 10 minutes.

Well, still haven't trapped the big yellow male, but I found Louie and brought him inside where he'll be safe until the tom cat is caught. Luckily he doesn't seem to be injured, just very scared right now.

Very happy to hear Louie's ok! Hope the little black cat shows up soon, too.

Keeping my fingers crossed that the tom's hunger will get the best of him and you'll get him trapped before too long.